Manufacture of deposited paper products



Patented Nov.

PAPER 7 PRODUCTS Leslie Stevens, Glen Ridge, N. J.

Application September 26, 1939, Serial No. 296,555

2 Claims. (Cl. 92-57) This invention relates to the manufacture of paper products by controllably variable fibrous deposition, and especially to the-production of loudspeaker diaphragms and the like by the deposition of pulp fibres on a sieve-like form.

The object of this invention is to make paper products such'as loud speaker diaphragms in a simple and emcient manner, while at the same time producing diaphragms'which are uniformly satisfactory both mechanically and acoustically andwhich will remain so throughout their lives.

The features of the invention will become ap-- parent from the following description taken in conjunction with the accompanying drawing; in

Fig. 1 is an elevational view of an apparatus for depositing cones;

Fig. 2 is a sectional view of the apparatus of l Fig. 1; taken along the line 2-2 of Fig. 1; Fig. 3 is a plan view of a cone deposited by the apparatus of Figs. 1 and 2;

Fig. 4 is an enlarged section of the cone of Fig.

I 3, taken along the line H thereof;

Fig. 5 is an elevational view of a modified form,

of apparatus for depositing cones; and

Fig. 6 is a sectional view of the apparatus of Fig. 5, taken along the line 66 thereof.

Referiing to Figs. 1 and 2, III is a cylindrical container supported upon a table II, the container being split horizontally near the bottom so as to form a lower'portion or base l2 and tion shown in Fig. 2.

upper portion I3 which arehinged together at M.

The two sections of the container may be locked together by a latch which is secured by links V I6 tothe base section i2, the latch fitting within arecess I 1 in the ring i8 secured to the upper section.

The ring l8- has a sealing gasket 20 secured therein which engages a similar gasket 2| secu'red to the base section so as to provide a liquid-tight joint between the two sections when they are locked together.

The center" of base section l2 communicates with a pipe 24 which extends downwardly therefrom. This pipe communicates with a water inlet main 25 through the valve 26 and also'communicates with an outlet pipe 21 through the. valve 28. These valves are manually operated by any suitable mechanism, the mechanism shown in Fig. 1 being diagrammatic only.

Removably mounted in the base section i2 is a conical form 30 containing a multitude of apertures so that it is sieve-like in construction and operation,- serving' asa screen. The base of the {porous form 30 engages a gasket ring 3| mounted inthe base section so that there is substantially no leakage around the base of the form. V I

Mounted on base section l2 and radially within the rim of form 30 is abaflle ring 32 having a' relatively sharp upper edge 33. This upper edge of ring 32 engages the under side of form 20 throughout its circumference,- so that there is substantially no leakage along'such line of engagement. For convenience, the portion of form 30 radially beyond the line 'of engagement of the baflle ring with the form is termed the rim portion, or zone, and designated 34 while the portion of form 30 radially within such line is termed the central portion, or zone, and designoted 35. The battle ring is provided with a number of holes 36 which afl'ord the only communicationbetween the areas tion 24 and under the central tively. of the conical form 30.

'In the use of the apparatus-in carrying out the method of the invention, the container ll is portion 35, respecinitially empty with its upper section I3 unlocked-- and turned back on its hinge. A form "is inserted in the apparatus, and the upper section I:

turned forward and locked by the latch I! to the lower section l2. The parts are'now in the posi- Water from the supply main is then introduced into the container by opening valve 26. When the. desired water level is attained, as may be determined by observing the gauge glass 31, the valve 26 is closed.

Thereupon a measured quantity of a prepared mixture of pulp and water is poured into the container In through the open top thereof and,

the pulp thoroughly mixed with the water already present in the container. This is conveniently done by agitating the mixture withpne or more air jets 38.

The outlet valve 28 is thereupon opened to allow the liquid to drain ofl'. During the draining of! period some of the liquid drains through the 'rim portion 34 of the form while the'rest drains through the central portion 35, the drainage starting through the two portions: substantially simultaneously. 7 I

Since the now of the liquid through the rim portion 34 is retarded by the baflle ring 32, less liquid drains throughthe rim portion '34 than through the central portion 35. The pulp, however. does not drain through the form. It is caught and deposited thereon over both the central and rim portions, less pulp being deposited over the rim portion 34 than :over the central portion 35in view of the different amounts of liquid draining through these portions. During this deposition the pulp fibersfelt together in heterogeneous directions, thus producing a conical diaphragm which, after drying, has no tendency to warp.

After all the liquid is drawn off, the apparatus 2 is opened up, the form with the diaphragm "deposited thereon removed, and the form and diaphragm placed in a suitable drying apparatus.

Whenthe diaphragmisdry, it is removed from the form and subjected to such supplementary I. OFF-HIE under the rim por-. i

operations as are desirable, for example, coating with a stifiening substance, trimming and pressins.

Figs. 3 and 4' show a diaphragm 40 made by this process, before being subjected .to such supplementary' operation. The rim portion 34a of the diaphragm is substantially thinner than the lably defined at the radius where the sharp edge 33 of baflle ring 12 engages the conical form 30.

The total weight of the diaphragm is determined by the amount of pulp contained in the pulp mixture poured into container 10, since all such pulp is deposited upon the form. By pouring into the container a measured amount of the mixture from a batch having known and unvaried proportions of pulp and liquid, the weight of the individual diaphragms produced by this method may be kept within narrow tolerances.

The'relative weights of the rim portion'ila 25 through the handle at the lower end thereof and and' the central portion 35a for different diaphragms are determined by the amounts of liquid' which pass through the respective portions of the form during the formation of the diaphragms.

I As these two flows start simultaneously, the relative weights of the two portions are determined by the difference in the rate of flow of these two. flows, except for the slight additional deposit on the outer portion after the liquid level has dropped below the upper portion. Thus, by re- .tarding the flow through the rim portion 34, accomplished by reducing the area of the passageways through baflie ring 32 (as by plugging up one or more holes 38, as with the threaded plugs 42) less of the total amount of pulp is deposited upon the rim portion 34 and more is deposited upon the central portion 35. The diaphragm formed when using reduced-areapassageways in the baille ring therefore has a thinner rim por-. tion 34a than the diaphragm formed when using full-area passageways in the baflle ring, other factors remaining the game. v

Diaphragms of any desired weight and of anydesired comparative thicknesses at the rim and central portions may thus be made by appropriate adjustment of the amount of pulp introduced into the container l and of the rate of flow of the liquid through a baiiie ring 32.

The line of demarcation or junction 4| between the rim portion 34a and the central portion 35a of the diaphragm is a true circular line of controllable definition concentric with the axis of v the diaphragm, thereby enabling the central portion 35a to propagate sound with a minimum of distortion.

The controllable rim portion 34a integral with the central portion 35a enables the diaphragm to be supported at the rim with a widely controllable load upon the sound-emitting portion of the diaphragm, and enables annular corrugations of widely controllable axial flexibility to be formed in the rim. These abilities open up an extremely wide range of acoustical requirements to which diaphragms made by this methodmay be accurately manufactured.

The manufacture of diaphragms by the foregoing process thus employs a single mixture of pulp and water, molds the entire diaphragm in one operation with the rim area thinner or thicker" than the central area, produces a diaphragm with excellent acoustical and mechanical properties which may'bevaried as desired, and maintained Referring to Figs. and 6, the apparatus there shown is in many respects identical to that shown in Figs. 1 and -2 and corresponding parts are designated similarly as in Figs. 1 and 2.

1 The apparatus of Figs. 5 and 6 contains an inner cylinder 50 the lower edge of which normally rests upon form 30, the diameter of inner cylinder 50 being substantially the same as that of baflie ring 32. The inner cylinder 50 extends to the top of container l0 and is prevented from moving laterally by the spacing pins 5| secured to inner cylinder 60 and projectingradiallyoutwarclly substantially to the inner surface of container ID; A ball 52 is secured to the upper por tion of inner cylinder 50, the bail passing through a slot 53 in an arm flpivotally mounted on the bracket 55 atthe top of container 10. Arm I4 extends past the pivot 56 and isbent downwardly to form a handle 51. A bolt 58 is threaded is secured in place by a nut 59. 1 The head of .the bolt extends toward the container I0 and in the normal position of the parts as shown the head is disengaged froma spring latch 60. 'However,

when thehandle 5'! is pushed-toward the container Hi, the head of bolt 58 engages spring latch 60 and the latter serves to hold the handle in the position to which it has been moved. In such,

position the arm 54 is raised above its normal 86 position, thereby raising inner cylinder 50 a short When this apparatus is charged, there is an outer annular body of liquid 34.1; between inner cylinder 50 and the wall .of container l0 and an inner cylindrical body of liquid 35:: contained within inner cylinder 50. V

In the use of the apparatus of Figs. 5 and 6, the container Ill is initially empty with its upper section I3 unlocked and turned back on its hinge.

Inner cylinderSO moves with the upper section A iorm 30 is inserted in the apparatusand the upper section l3 swung forward and locked by the latch l5 to the lower section l2. The handle 51 is pulled outwardly so that the lower end of the inner cylinder rests upon form 30. The parts are now in the position shown in Fig. 6.

Water fromthe supply main is then introduced into the container by opening the valve commu- When the desired water nicating with pipe 24. level is attained, this valve is closed. Thereupon a measured quantity of a prepared on mixture of pulp and water is poured into the .body.

of liquid, 35:]: and a measured quantity of another prepared mixture of pulp and water differing in;

constituents or in concentration, or both, from the mixture poured into the body of liquid at j is poured into the body of liquid 34x. 'I'hereupon each body of liquid is thoroughlyagitated to distributethe pulp in suspension in theliquid, separate air jets being 'used in the different bodies of liquid, air jet 38 being in theouter body of '70 liquid 34a: and air jet 38 being in the inner body of liquid 35m.

The outlet valve communicating with pipe 24 is V thereupon opened'to allow theliquids to drain oiT. The outerbody of liquid 34:: drains through the rim portiontl' of the form while the innerv '5 body of liquid 35m drains through the central portion 35 of the form, The pulp in suspension in the outer body of liquid 34x is thus deposited upon the rim portion 34 and the pulp in suspencylinder 50 and maintain it raised, by the latch 60, through the remainder of the depositing period. The two pulp mixtures thus intermingle at the surface of the form beneath the lower end of inner cylinder 50 and as a consequence the deposited fibers at that region are an intermixture of fibers from the two pulps. This intermixture of fibers serves to knit the rim portion 34a of the resulting cone with the central portion 35a thereof.

Bafiie ring 32 enables the rate of flow of the outer body of liquid 34a: to be adjusted to such a value that the drainage of the outer body of liquid Ilawill be completed at substantially the same time as the drainage of the inner body of liquid 350:. As a consequence this eliminates the tendency, when the two bodies of liquid drain in different times, for the slower body of liquid to drain or slop over on to the portion of the form on which the faster body of liquid deposits its pulp. In other words, there is in such cases a tendency toward irregularity in production and an indeterminate, indistinct and non-circular line of demarcation between the rim area 34a and the central area 35a ofthe resulting cone. These irregularities and uncertainties areaeliminated by the use of the bafile ring 32.

tion, as the apparatus readily accommodates forms of different angles, shapes, and outer limits of perforations, as well as bafile rings of difierent diameters and heights.

While the invention has been described in connection with the production of a diaphragm for loudspeakers, it is not confined thereto, but is intended to cover the similar controllably variable production of deposited paper products.

I claim:

1. Apparatus for. forming one-piece coneshaped articles having an annular outer section thinner than the center inner section, a vertically sustained cylindrical container having a centrally located drainage opening in the bottom thereof'and an annular shoulder in the side wall thereof at a horizontal level above the bottom with a fluid permeable conically shaped former member seated by its periphery on said shoulder, an

provide a determined rate of flow of fluid through After all the liquid is drawn oil the apparatus is Opened up and theform and diaphragm hanoperation to produce an integral diaphragm in which the respective areas are sharply defined by a circular line of demarcation coaxial with the diaphragm and yet felted together in a continuous fibrous unit. Thus the resulting diaphragms have uniformly excellent acoustical and mechanical properties.

the partition member to the drainage opening less than that through the central portion of the former member to the drainage opening, means to fill the cylindrical container to a determined horizontal level with water and to suspend a measured quantity of pulp suspension in the water above the former member and means regulating the rate of flow of said water through the said drainage opening. I

2. Apparatus for forming one-piece coneshaped articles having an annular outer section thinner than the center inner section comprising a vertically sustained cylindrical container having a centrally located drainage opening in the bot tom thereof and an annular shoulder in the side wall thereof at a horizontal level above the bottom witha fluid permeable conically shaped former member seated by its periphery on said shoulder, an annular partition member seated on the bottom of said container and concentrically disposed about the said drainage opening, the upper edge of said partition member bein knife-edged and contacting the under surface of the said former member, said partition member being provided with a plurality of openings therethrough. the number and diameter thereof being selected to provide a determined rate of flow of fluid through the partition member to the drainage opening less than that through the central portion of the former member to the drainage opening, a cylindrical partition member located centrally with- The two-mixture apparatus of Figs. 5 and 6 is quickly changed to the single-mixture apparatus of Figs. 1 and 2 by lifting out the inner cylinder Although, in both the single and double-mixture apparatus, the water is most conveniently introduced into and drawn from the container I 0 in and drained out in different manners, suchas by the manner shown, the water may be introduced lowering and raising the container, respectively,

in the container above the former member having a diameter approximating that of the annular partition member, the bottom of said cylindrical partition member being provided a knife edge, means to raise and lower the said cylindrical artition member out of and into knife edge contacting position with the upper. surface of said former member, means to fill the container with water to a determined horizontal level and to suspend a measured quantity of pulp suspension of different compositions inside and outside the said 

